Balanced rotary brush



April 23, 1957 A. T. scHoFlELD 2,789,302

BALANCED ROTARY BRUSH Filed June 29, 1954 2 Sheets-Sme# 1 Hlm" RINVENTOR. ART/Me scanf/Lp MMM April 23, 1957 A. T. scHoFlELD L BALANCEDROTARY BRUSH Filed June 29, 1954 2 Sheets-Sheet 2 A INVENTOR. ARTHUR 7:SCHOf/ELD A TTo/Q/veys Osborn Manufacturing Company, Ceveiand, Ohio, acorporation -of Ohio Application June 29, 1954, Serial No. 440,083

14 Claims. k(Cl. 15-17i-9) This invention relates as indicated to arotary brush, and more particularly to an annular ,rotary brush having aback member and a retaining member operative to secure and retain thebrush material 'in such back.

While not 'limited thereto, my invention is particularly suitable andadvantageous when employed in conjunction with the form of brushconstruction disclosed and claimed in Whittle Patent 2,288,337. It mayalso be utilized, however, in other forms of brush construction havingannular channelform backs and retaining elements such as wire loops andsheet metal washers for holding the brush material in place.

Of recent years there has been Yan increasing tendency to utilize powerdriven rotary brushes vgenerally as precision tools for the ,performanceof many very delicate brushing operations, and 'it has vconsequentlybecome ymore and more important that 'the density of brush material llhe uniform, that the brush trim be uniform and to precise specications,and that the brush .be very accurately balanced especially for highspeed operation. Despite improvements 'in the measuring .of the brushbristle material and finishing of the brush surfaces, .it has been foundthat under conditions of :use and particularly when operated at highspeeds for considerable periods of time, annular rotary brushes tend tobecome .out of balance, if this is not already the case. This militatesagainst their efficient use .in many types of applications. After 'muchinvestigation, it was determined Vthat the principal -cause .of thisditculty ,is the shifting vof the retainhig element eccentricallytof thebrush .axisand brush back. Such shifting not only serves to throw thebrush oit balance but also .permits loosening of 4a portion ofthe brushmaterial with consequent shifting of such material circumferentia'llyand also, `in .some cases, shedding. This situation is particularlylikely to .be prevalent when employing brush bristle material such ascrimped wire, bundles of .the latter frequently :being very dissimilarin their compressibility `even when ,of Valmost exactly the same weight.In the Whittle .type of brush construction above referred to, if several.of the more compressible bundles of Vbrush material 4are distributedontone side of the brush back, Vthe retaining :member will shifteccentrically while being shrunk down upon :the .brush material inaccordance with the Whittle teaching.

It is accordingly a l,plincipal object ofgmy invention to provide arotary brush wherein the brush -bristle material is retained ,in placeby .a retaining element positively located .and spaced toprevent-development-of eccentrici'ty and imbalance.

Another -object is to provide ysuch brush .in .the form of an annularsection such tas that taught in Whittle Pa-tent 2,288,337.

Still Ianother object is to provide means in Aconjunction with suchretaining element positioning means :adapted to assist in seating thebrush element :upon an appropriate hub -or adapter.

A further object is to provide such brush in lwhich `2 the `brushmaterial is rmly held against shedding and also against shiftingcircumferentially of the brush.

Other objects of the invention will appear as the description proceeds.

VTo the accomplishment of the foregoing and related ends, said inventionthen comprises the features hereinafter fully described and particularlypointed out in the claims, the following description and the annexeddrawing setting forth in detail `certain illustrative embodiments of theinvention, these being indicative, however, of but a few of the variousways in which the principle of the invention may be employed.

ln said annexed drawing:

Fig. l is an end View of a rotary brush of the vgeneral type taught inA'Whittle 'Patent 2,288,337 modified in accordance with my invention;

Fig. 2 is a transverse radial section taken on the line 2-2 on Fig. l;

Figs. 3 and 4 are two fragmentary transverse sections illustratingstages in the manufacture of my new brush;

Fig. '5 is a fragmentary section circumferentially of the brush backtaken on the line 5 5 on Fig. l;

Figs. 6 and 7 are enlarged Vtransverse sections generally similar toFig. 2 but showing ,steps in the production of a somewhat modified ,formVofbrush assembly utilizing a sheet metal Washer as the brush materialretaining elcment;

Fig. 8 resembles Fig. 7 but with a wire retaining element;

Fig. 9 is a fragmentary view of .an annular brush element as shown inFig. l mounted von ,a special hub or adapter;

Fig. l0 is a transverse Asection .taken on Vthe line ill-dii on Fig. 9;and

Fig. ll is a 'fragmentary View of a backing strip having special yteethor supporting elements welded thereto.

Now referring `more particularly `to said annexed drawing, theembodiment illustrated -in Figs. Vl, 2 and 5 comprises a sheet metalchannelform annulus the sides 2 and 3 of which extend radiallyoutwardly. Such annulus may desirably be formed by circularizing a stripof sheet metal and joining vthe opposed ends by means of a weld 4, suchweld being of substantially .the same thickness as the remainder of Vthestrip .so vas vnot to afford Va source of unbalance. Brush material suchas bristles 5 are doubled about `an annular retaining .element -6-within `the brush back channel with the slightly Yflaring brushmaterial extending generally radially from the latter. y[he back i' andretaining element t6 are preferably :assembled in the general mannertaught in Whittle Patent 2,288,337, modified however Vby the tact thattransverse teeth or projections 7 4are Astruck up at intervals from thecenter portion of the backing strip 1, such teeth extending radiallyoutwardly `and leaving corresponding holes or apertures 8 in the innerperipheij, of the circularized strip. The crowns of such teeth willpreferably 'be somewhat concave or notched las shown in order Vto assistin centering the retaining element L6.

In Vassembling the brush, the annulus 1 `with the `series of radiallyprojecting .teeth '7 is :somewhat dared Yat one end 9 and a somewhatnarrower sheet metal Aanmrlus 6 of outwardly concave cross-section is`centered over such teeth-as show-nin Fig. The measured bundles of`brush bristle material are next inserted between the -two annali, suchteeth serving to .assist in .maintaining accurate uniformcircumferential distribution of Athe bristle material. The other `edge10 of strip 1 is now also dared .as Vshown in `Fig. 4 and a sufficientlystable assemblt is thereby .produced to permit handling and placing uponan appropriate press whereby such flared edge portions 9 and lll areforced toward each lother to "orm the' annular channel- 'form brush backof general -U-shap'ed cross-section as 3 shown in Fig. 2. Such formingoperation serves also laterally to compress the concave retainingelement 6 to collapse the same as shown in Fig. 2. As explained inWhittle Patent 2,288,337, such lateral compression of.-1`etainingelement 6 is effective to produce radially inward shrinking of suchannulus irmly to compress and secure the brush bristles 5 within thechannel back 1. The density of brush bristle ll and the height of theprojections 7 are selected so that upon such vshrinking of annularretaining elernent 6 Vthe latter is exceedingly firmly seated againstsuch projections and the brush bristle material is very densely andfirmly compacted intermediate element 6 and channel back 1. It will, ofcourse, at once be apparent that projections 7 serve to prevent anyshifting of annulus 6 eccentrically of back 1, and this major cause ofbrush unbalance is accordingly eliminated.

As also taught in Whittle Patent 2,288,3 37, the sides 2 and 3 of theannular back may be locally compressed to form radial grooves 11extending from the outer edges of the channel sides to the innerperiphery of the back and thereby affording Ventilating passages when aplurality of the annular sections are assembled side by side uponappropriate hubs or adapters.

Now referring to Figs. 6 and 7 of the drawing, a soniewhat modified formof assembly is illustrated. The teeth 7 are notched as at 12 to receiveand center a fiat sheet metal washer 13, the inner diameter of which issufficiently large to clear the crowns of the radially extendingprojections 7 during initial assembly (Fig. 6). The annular channelformback 1 is then expanded over an appropriate forming die to seat washer13 rmly in notches 12 (Fig. 7), thereby finally compacting the brushbristle material 5 between such retaining element 13 and the back 1 andValso permanently centering retaining element 13 both radially andlaterally of the assembly.

In the Fig. 8 embodiment of my invention, I utilize a wire retainingelement 14 which may be seated in notches 15 of teeth or projections 7in the same manner as washer 13 or which may alternatively be thusseated simply by tensioning the wire and then securing the ends of thesame together as by welding or twisting. In other words, this type ofretaining element may either be shrunk down upon the projection 7 or thechannel back 1 may be expanded toV engage the same. When the'wireretaining element 14 is employed, it may be desirable somewhat tocompress the radially outward opening of back 1 to atford a constrictedpressure neck.

As shown in Fig. l1, teeth or projections 18 generally equivalent toprojections 7 may be formed in various ways other than by punching themup from the inner periphery of annulus 1. Thus, as shown in Fig. 11,such teeth may be spot welded as at 19 to such annulus.

When the teeth or projections 7 are punched up from strip 1 as describedabove, leaving equally circumferentially spaced openings 8 in the innerperiphery of the annular channelform back 1, such openings may beutilized to assist in the seating of the annular brush section on anappropriate hub or adapted as illustrated in Figs. 9 and 10, forexample. In the form illustrated, such adapter comprises an annularportion 20 adapted to lit on an appropriate arbor or mandrel and havingspokes 21 extending radially therefrom. Such spokes have arcuate endportions 22 adapted to bear against and support the inner periphery ofchannel back 1 and are also provided with radially outwardly protrudingbuttons 23 adapted to be pressed into the openings 8 and thereby toassist in securing the annular brush section against rotation relativeto the adapter on which it is mounted. Such adapters may be ofcardboard, vulcanized ber, synthetic plastic, and other suitablematerials. When formed as shown, they may be snapped in place withrelatively little effort and yet atord means for proper driving of thebrush as well as seating and centering the same. An adapter having aroughened outer periphery adapted to seat the annular brush section maysimilarly be employed, such roughened periphery drivingly engaging theopenings 8.

Any of the well-known brush bristle materials may be utilized such as,for example, horsehair, tampico fiber, crimped wire, nylon, plasticcoated wire, and plastic coated glass iiber strands. The channel backand retaining element will usually be of sheet metal such as steel butother appropriate materials may obviously be employed depending on theuse intended.

When forming the teeth or projections 7, it is desirable to use a doubledie to score the bristle side of the annulus 1 before punching up theteeth, thereby to avoid sharp edges on the teeth and the holes 8 whichmight otherwise eventually tend to cut some of the adjacent brushbristles. By rounding the corners of such teeth or projections, thedevelopment of undesirable stress concentrations is also avoided.

It will be apparent that not only have I provided a balanced rotarybrush suitable for high speed operation, but also such brushconstruction serves to prevent circumferential shifting of the brushbristle material. Accordingly, brushes of this type may be produced tovery precise and accurate specifications and will maintain the desiredcharacteristics through long periods of use.

When inserting the brush bristle material it is desirable to selectbundles of bristles of a size to permit achieving the required densityby insertion of an evenV number of bundles between adjacent projections7. This much facilitates the obtaining of uniform circumferentialbristle distribution and even balance.

Other modes of yapplying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

l therefore particularly point out and distinctly claim as my invention:

l. ln an annular rotary brush section comprising an annular sheet metalcontinuous channel back opening radially outwardly, an annular retainingelement within said channel, and brush material secured beneath saidretaining element in said channel and extending generally radiallytherefrom in a substantially uninterrupted layer; a plurality of thintransverse radial projections on said back within said channelsubstantially uniformly distributed about the circumference thereofpenetrating said brush material and engaging the inner periphery of saidretaining yelement to maintain the latter con-centric with said back.

2. in an annular rotary brush section comprising an annular sheet metalchannel back opening radially outwardly, an annular retaining elementWithin said channel, and brush material secured beneath said retainingelement in said channel and extending vgenerally radially therefrom; aplurality of thin transverse radial projections on said back Within saidchannel substantially uniformly distributed about the circumferencethereof, said projections having concave radially outer transverse edgeportions with the inner periphery of said retaining element firmlyseated Ithereon to maintain said retaining element concentric with saidback.

3. In an annular rotary brush section comprising an annular sheet metalchannel back opening radially outwardly, an annular retaining elementwithin said channel, and brush material secured beneath said retainingelement in said channel 'and extending generally radially therefrom; aplurality of thin transverse radial projections on said back within saidchannel substantially uniformly distributed about the circumferencethereof, said projections wardly, an annular retaining element withinsaid channel, and brush material secured beneath said retaining elementin said channel and extending generally radially therefrom; a pluralityof thin transverse radial projections on said back within said channelsubstantially uniformly distributed about the circumference thereof,said projections having notched radially outer transverse edge portionsWith the inner periphery of said retaining element firmly seated thereonto maintain said retaining element concentric with said back, saidretaining element comprising la flat sheet metal ring engaged in suchnotches.

5. In an annular rotary brush section comprising an annular sheet metalchannel back opening radially ontwardly, an annular retaining elementwithin said channel, and brush material secured beneath said retainingelement in said channel and extending generally radially therefrom; aplurality of thin transverse radial projections on said back Within saidchannel substantially uniformly distributed about the circumferencethereof, said projections having notched radially outer transverse edgeportions with the inner periphery of said retaining ele- -ment rmlyseated thereon to maintain said retaining element concentric with saidback, said retaining element comprising a Wire ring engaged in suchnotches.

6. In an annular rotary brush section comprising an annular sheet metalchannel back opening radially outwardly, an annular retaining elementwithin said channel, and brush material secured beneath said retainingelement in said channel and extending generally radially therefrom; aplurality of thin transverse radial projections on said back within saidchannel substantially uniformly distributed about the circumferencethereof, said projections having concave radially outer transverse edgeportions with the inner periphery of said retaining element firmlyseated thereon to maintain said retaining element concentric with saidback, said retaining element comprising a sheet metal ring of collapsedU-shaped cross-section, the base of such U projecting inwardly andengaging such concave edges of said projections.

7. In an annular rotary brush section comprising an annular sheet metalchannel back opening radially outwardly, fan annular retaining elementwithin said channel, and brush material secured beneath said retainingelement in said 4channel and extending generally radially therefrom; aplurality of thin transverse projections punched up from the innerperiphery of said back and extending radially within said channel, saidprojections being substantially uniformly distributed about such back`and Ermly engaging the inner periphery of said retaining element tomaintain the latter concentric with said back.

8. In an annular rotary brush section comprising an annular sheet metalchannel back opening radially outwardly', an annular retaining elementwithin said channel, and brush material secured beneath said retainingelement in said channel and extending generally radially therefrom; aplurality of thin transverse projections punched up from the innerperiphery of said back and extending radially within said channel, saidprojections being substantially uniformly distributed labout such backand firmly engaging the inner periphery of said retaining element tomaintain the latter concentric with said back, and an annular adapterseating such inner periphery of said back having protuberances lengagedin the openings left in said back by said punched-up projections.

9. In an annular rotary brush section comprising an annular sheet metalchannel back opening radially outwardiy, an annular retaining elementWithin said channel, and brush material secured beneath said retainingelement in said channel and extending generally radially therefrom; aplurality of thin transverse projections punched up from the innerperiphery of said back and extending radially within said channel, saidprojections being substantially uniformly distributed about such backand firmly engaging the inner periphery of said retaining element tomaintain the latter concentric With said back, and a rotatable hubhaving an outer periphery seating such inner periphery of said back andengaging in the openings left in said back by said punched-upprojections.

10. The method of forming an annular rotary brush section whichcomprises forming a cylindrical sheet metal ring, punching up aplurality of radially outwardly protruding thin transverse teeth on suchring, said teeth being uniformly distributed circumferentially of suchring, placing uniform quantities of brush material intermediate suchteeth generally parallel to the axis of such ring, fitting a secondcylindrical sheet metal ring over such teeth and brush material-co-axially with such first ring, forming both such rings to radiallyoutward U-shaped :cross-section to retain su-ch brush material withinsuch first ring by such second ring, and `collapsing the sides of suchsecond U-shaped ring to shrink such ring down on such teeth in rigidconcentricity with such first ring, such teeth penetrating such brushmaterial.

11. The method of forming an annular rotary brush section whichcomprises forming a ycylindrical sheet metal ring, forming a pluralityof radially outwardly protruding thin transverse teeth on such ringdistributed circumferentially thereof, placing brush materialintermediate such teeth generally parallel to the axis of such ring,tting a second cylindrical sheet metal ring of shallow U-shapecross-section over such teeth and brush material co-axially with suchfirst ring, forming such first ring to radially outward U-shapecross-section with such second ring retaining such brush materialtherewithin, and ycompressing the sides of such second ring toward eachother to shrink such ring down on such teeth in rigid concentricity withsuch first ring, such teeth penetrating such brush material.

12. The method of forming a rotary brush which comprises interposingcompressible brush material between a central circular support and anouter ring, providing circumferentially distributed thin rigid spacingelements between such support and ring, and shrinking such ring down onsuch elements in rigid concentricity with such central support, suchthin rigid elements penetrating such brush material.

13. The method of forming a rotary brush which cornprises interposingcompressible brush material between a central circular support and anouter ring, providing circumferentially distributed thin rigid spacingelements between such support and ring, and expanding such supportrigidly to engage such elements with the inner periphery of such ring tohold the latter concentric with such support, such thin rigid elementspenetrating such brush material.

14. In an annular rotary brush section comprising an annular sheet metalchannel back opening radially outwardly, an annular retaining elementwithin said channel, and brush material secured beneath said retainingelement in said channel and extending generally radially therefrom; aplurality of thin transverse projections punched up from the innerperiphery of said back and each extending radially within said channelan equal distance outwardly therefrom toward said retaining element,said projection being substantially uniformly distributed about saidback accurately to tix by their outermost edges the radially innermostdistance to which said retaining element may contract during theassembly of said brush.

References Cited in the file of this patent UNITED STATES PATENTS1,800,376 Cornell Apr. 14, 1931 2,288,337 Whittle June 30, 19422,409,309 Peterson Oct. 15, 1946 2,616,111 Vose Nov. 4, 1952

